1. Field of the Invention
The present invention relates to an electronic control brake system. More particularly, the present invention relates to an electronic control brake system capable of ensuing pedal force upon regenerative braking or brake-by-wire control.
2. Description of the Prior Art
In general, as illustrated in FIGS. 1 and 2, an electronic control brake system 1 having a simulation function comprises a brake pedal 30 operated by a driver, a master cylinder 10, a hydraulic adjusting unit 40, an electronic control unit 80, a brake pedal displacement sensor 31 and a simulation chamber 33. The master cylinder 10 amplifies force transferred from the brake pedal 30 to generate brake fluid pressure. The hydraulic adjusting unit 40 is provided with a plurality of inlet valves 46 and a plurality of outlet valves 45 to supply hydraulic brakes 50 with the fluid pressure. The electronic control unit 80 controls the hydraulic adjusting unit 40. The brake pedal displacement sensor 31 is provided at one side of the brake pedal 30 to detect displacement of the brake pedal 30 and provides the detected displacement to the electronic control unit 80. The simulation chamber 33 is provided at one side of the master cylinder 10 to simulate stepping force of the brake pedal 30.
An oil tank 20 is provided at one side of the master cylinder 10 to provide oil to the master cylinder 10 and a hydraulic pump 41 of the hydraulic adjusting unit 40.
The hydraulic adjusting unit 40 is provided with the inlet valves 46, which are controlled by the electronic control unit 80 to adjust supply of oil to the hydraulic brakes 50, and the outlet valves 45 that are controlled by the electronic control unit 80 to adjust oil exhausted from the hydraulic brakes 50.
If the electronic control brake system 1 having the simulation function performs a normal mode, a hydraulic pump motor 42 and the hydraulic pump 41 are driven, so that oil is filled in an accumulator 43 at desired pressure. At this time, if a driver steps on the brake pedal 30, the brake pedal displacement sensor 31 detects the displacement of the brake pedal 30 to provide the electronic control unit 80 with the detected displacement. Then, the electronic control unit 80 opens the inlet valves 46 in accordance with the displacement of the brake pedal 30. Thus, the high pressure of oil stored in the accumulator 43 is introduced into the hydraulic brakes 50, so that a braking operation can be performed.
However, when the electronic control brake system 1 having the simulation function performs regenerative braking or brake-by-wire control, pressure of the master cylinder 10 is not adjusted, so that pedal force may not be ensured.
Further, braking performance of a vehicle may be degraded, causing traffic accidents.